On Thursday, April 18, 2019 07:31:13 PM DK1IS wrote:

SNIP

> Anyway, the idea is fascinating. Having no VLF crystals up to now, I

> made some preliminary tests with a randomly available HC-6-U quartz, QRG

> 2434 kHz, wavelength 123 m. And yes, it works!

>

> * TX: Sythesizer Schomandl MG100M, 300 Hz ... 100 MHz, smallest step

> 0.1 Hz, Ri = 50 Ohms, P = 10 dBm, output tied to first leg of

> quartz, alternatively direct to the antenna wire

> * RX: Perseus SDR with an active rod antenna on my garage, fed by a

> solar system, no external wire connections, air-line distance 100 m

> to my shack

> * Antena wire: 2 m or 4 m, laid out in the shack, tied to second leg

> of quartz, alternatively direct to the TX output

>

> Results with 2 m antenna wire:

>

> * with quartz resonator: fres = 2,433,908.8 Hz, RX level at resonance

> = - 63,1 dBm, - 3dB-bandwidth = 48.3 Hz resulting in Q = 50391

> * without quartz resonator: RX level = - 85,4 dBm resulting in a gain

> of 22.3 dB with quartz

> * comparision: my 13 m T-Marconi with top load 4 x 33 m, tuned to 2434

> kHz and fed by the synthesizer with 10 dBm results in a RX level of

> - 32.1 dBm ;-)

63.1 dBm - 32.1 dBm = 31.0 dB : the quartz adapted antenna radiated power is 1/1000 respect the T-Marconi, so the efficiency is 0.1%

Good DX ;-)

Claudio, IK2PII

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